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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 68 (1997), S. 3540-3543 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: This work describes the characteristics of a bench station designed for both the control of the operational parameters of a unitary, low temperature fuel cell and the data acquisition for performance evaluation. The controlled parameters are the current through the cell, the pressure and the flow of the reactants, and the temperature of the cell and of the gaseous reactants. The system measures the potential drop across the cell and the potential of each electrode with respect to a reference, as a function of the current, which is varied on a predetermined interval. The program plots the results and fits the experimental curve to a theoretical expression, which allows the determination of the cell resistance and the Tafel kinetic parameters of the cell reactions. The test station provides a rapid route to the work with single/half cells in the evaluation of materials and fuel cell performance. The computer controlled procedures, data acquisition, and analyses proposed here substitute with advantages time consuming manual procedures. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of applied electrochemistry 12 (1982), S. 405-410 
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract A correlation between specific adsorption and corrosion inhibition was made on the basis of calculations of the degree of coverage at zero charge on the electrode and corrosion rates. 1-butylpyridinium bromide (BPB) was choosen as a model compound for these studies. The electrical double-layer parameters were determined at constant charge on a mercury electrode, from values of the interfacial capacity and surface tension obtained experimentally from aqueous solutions of BPB at 25° C. The characteristics of the salt as a corrosion inhibitor were studied through Tafel plots and weight-loss measurements using mild steel plates immersed in H2SO4 solutions. Analysis of the results lead to the conclusion that the salt adsorbs intensely on the metal surface, forming a complete monolayer of BP+ ions in 0.1 mol dm−3 solutions and multilayers for higher concentrations. The results of this work indicate that for high coverages there is a good correlation between the amount of BP+ specifically adsorbed on mercury and the inhibition of the corrosion process on mild steel. That type of compound acts mainly as an anodic inhibitor in acid media by the formation of protective layers on the metal surface.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of applied electrochemistry 26 (1996), S. 297-304 
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Electrochemical studies on low catalyst loading gas diffusion electrodes for polymer electrolyte fuel cells are reported. The best performance is obtained with an electrode formed from 20 wt% Pt/C, 0.4 mg Pt cm−2 and 1.1 mg Nafion® cm−2 in the catalyst layer and 15% PTFE in a diffusion layer of 50 µm thickness, for both the cathode and the anode. However, it is also observed that the platinum requirement can be diminished to values close to 0.2 mg Pt cm−2 in the cathode and 0.1 mg pt cm−2 in the anode, without appreciably affecting the good characteristics of the fuel cell response. The experimental fuel cell data were analysed using theoretical models of the electrode structure and of the fuel cell system. It is seen that most of the electrode systems present limiting currents and some also show linear diffusion components arising from diffusion limitations in the gas channels and/or in the thin film of electrolyte covering the catalyst particles.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of applied electrochemistry 27 (1997), S. 19-24 
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract In this work results on the preparation, characterization and single cell testing of matrices for phosphoric acid fuel cells are reported. The matrices were produced using mixtures of powders of silicon carbide with zirconium silicate or niobium carbide, by deposition of an aqueous emulsion of the powders on top of the catalyst layer of the gas diffusion electrodes, or by making a self-supported film of the materials. The physical characterization of the powders and of the matrices included the distribution of particle size and shape of the powders and the thickness, electrical resistance, and pore size distribution in the matrices. The matrices were evaluated under operation, using standard supported platinum on carbon gas diffusion electrodes in a H2O2 single fuel cell setup operating with phosphoric acid at 180. The results of the cell potential; current density characteristics were analysed to separate the contribution of the structural properties of the matrices on the total polarization losses of the single cells. It was found that a single cell operating with a self-supported matrix composed of 50wt% NbC+SiC has a much better performance than that observed with SiC alone.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of applied electrochemistry 22 (1992), S. 973-977 
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract This paper describes the preparation of Ni−Zn and Ni−Co−Zn coatings by electrodeposition on a mild steel substrate. After treatment in a KOH solution to leach out part of the zinc, the materials were evaluated as cathodes for the hydrogen evolution reaction in alkaline solutions. The materials were found to have high surface areas and low Tafel slopes. Overpotentials at current densities of technological interest are significantly lower than those of the traditional materials used in water electrolysis.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of applied electrochemistry 22 (1992), S. 888-892 
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The characteristics and mechanism of the hydrogen evolution reaction on a nickel sulphide electrode incorporating molybdenite particles are described. At 25°C the overpotential for the reaction is 300 mV lower than that of the mild steel cathodes used in unipolar electrolysers. The material shows good stability under long term operation.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of applied electrochemistry 23 (1993), S. 1151-1161 
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract A resistive grid model was used to study the current and ohmic overpotential distributions along the surface of lead-acid battery electrodes. Analyses were made under two different regimes: the initial behaviour at high current densities and the response with time at low current densities. At high discharge currents the theoretical results show that the geometry of the electrodes and the position of the lug play the most important role in controlling the magnitude of ohmic losses. The best geometry is a square grid with the lug positioned at the upper centre of the electrode. At low discharge currents the model was used to follow the current distribution along the electrode surface as a function of time. In this last study the appearance, for long discharge times, of short-circuited concentration microcells localized in certain regions of the electrode surface was noted. The other regions of the electrode supply the external discharge current and the excess current necessary to charge the internal microcell.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Usually, an increase in the temperature of operation leads to a reduction in the voltage of operation of commercial water electrolyzers. The present work analyzes this effect in connection with the overpotential of the hydrogen and oxygen evolution reactions on electrodeposited nickel and some nickel-based codeposits which under normal operational conditions have shown good electrocatalytic characteristics. Results on pure nickel are also presented for comparison. A pressure chamber, adequate for electrochemical studies at high temperatures and pressures is described.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of applied electrochemistry 23 (1993), S. 641-645 
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Electrodeposited Ni-Zn and Ni-S on a mild steel substrate have shown very good performance as cathode materials for the HER in alkaline media. The materials were studied previously with surface techniques and evaluated through current-potential curves and long term operation. This paper describes a detailed mechanistic study of the HER on Ni-Zn and Ni-S carried out with impedance techniques. In both cases the reaction proceeds through a Volmer-Heyrovsky mechanism. As predicted by kinetic theory, the temperature study shows that the energy of activation of the rate determining step is the same as the energy of activation of the overall reaction.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 2 (1981), S. 221-224 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The study of the structure of the electrode-solution interface usually involves the measurement of the differential capacity-potential characteristics of the system. In order to obtain the double-layer parameters from these data, integration and differentiation procedures are required and, for this purpose, the use of computational methods is of great value. Two computer programs have been written for the treatment of data for the adsorption of neutral molecules on electrodes. The programs use the charge density and the electrode potential as the electrical variable, respectively, and, in both cases, the differentiation procedures have been optimized by the use of an adequate numerical function. The advantages of doing a simultaneous analysis on both electrical variables are pointed out.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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